Problems keeping Z0

[mdcavanaugh]

Twice now I've had an issue with with Z axis not keeping the correct 0.

First, it was cutting out plastic pieces- ~.75" by ~1.25" and .38" thick (at .07" pass depth). There were 9 of them, and the first 3 cut perfect, so I left the boot on and left the machine unattended for 5 min... When I came back, the Z had shifted down over the course of the next three pieces (~-.1" each time), such that it started ~-.3" on first pass and ended up cutting through the sac. board and into the table itself by the end. When I stopped the machine, it is hard to say exactly how far the Z0 was down from original, but it was quite a bit. The pieces were designed in VCarve Pro 7, and I've had plenty of success using the same method- there seems to be nothing wrong with the G-code.

Just now, I was carving an ornate Eagle (~4.5" by 10" and ~.65" deep) in .75" thick walnut board. I paused the finishing toolpath for about 10 seconds to re-clamp the boot on the machine, about half way through the run. Everything looked good, but when I continued the run, the Z shifted about 2" down! It drilling my engraving bit right into the table not even a second after pressing continue. These toolpaths were made in Cut3D, which I also have had plenty of success with.

Is anyone else having any issues like this?

[gordread]

I've also had problems with the machine retaining Z0. For example, it may drop (or sometimes raise) up to 0.2" during the cut (ie, when I press the 'go to 0,0,0' it will center perfectly (x,y) but will remain slightly elevated (z).

I don't think I've had it where it ploughs into the bed though.

I know that doesn't help, but maybe there are others?

(Yes, I keep the machine lubricated and clean).

Gordon

[Wolffie1]

Sounds like you are having a problem with the weight of the boot pulling the axis down.
Cheers
Wolffie

[renicolai]

I have experienced the same problem of the Z direction floating. I have had the machine for about 2 months and for the first month everything worked fine. But within the last two weeks the Z home position tends to adjust by it self upwards, so that the bit is cutting air. After pausing and then aborting the tool path I cycle the tool bit back to the home position, (i.e. x, y, z, all zero) the new position is above the work piece about where the bit was cutting air. The offset of the z home position varies between .1 inch to .5 inch. If a new home position is defined at the work piece top surface, the same thing occurs but at a different offset. When I called the support desk for help, they could not offer any solution except to disconnect the z cable from the control box and reconnect. That did not help. I have tried to use some of the tool paths that were working the during the first month that I had the machine and now they do not work either.
If anyone has a solution, I would also appreciate sharing the answer. As of now I have a machine that does not work or can be trusted.

[GullyFoyle]

Not sure if this helps, but the 3d printer forum people prefer to print from sd card instead of via USB
I guess USB can cause errors.

[sk8nmike]

Most of the time Z axis trouble is caused by the router or the bit slipping. Keep you collet clean and make sure the bits are tight. Check your router make sure it's tight in the holder. I prefer to loosen one of the mounting bolts, tighten the cinch bolt then re-tighten the mounting bolt.

[gordread]

Guys, that's a really good point about router slippage. I've not noticed any differentiation in z-height lately, and that may simply be because the router is completely as low as it can be in the holder. Maybe it is worth investing in one of those aluminum holder I've seen on the site. Hmm....

Gordon

[dstranz]

On my first trial run with the new CNC, the router slipped in the plastic holder, gouged a groove across the workpiece and continued to drive through the backing board and into the aluminum platform before I realized what was happening and could hit the e-stop.

For a temporary fix, I bought two 4" hose clamps and put them around the router body just above the clamp. That locked it into position and kept it from drifting downward as far as I could tell. With that fix, I then machined two 3/4 clamps out of 7-ply Baltic birch plywood using the original clamp as a model. I sandwiched them together with Titebond, and those will go onto the router this weekend. My plan is to put them first, the original plastic clamp above that, and for paranoia, a hose clamp above that. I'm not prepared to let a $4000 machine destroy itself if I turn my back on it because of a defectively designed clamp.

You simply can't clamp the plastic tightly enough, especially with the non-slip nuts, and even if you do get it tight, the plastic will deform over time and the router will loosen. One would hope the NWA folks are paying attention to these clamping issue posts and will offer an aluminum replacement as an upgrade, preferably free for those of us who would be happy to send in a photo of our gouged decks.

[Rosscoinc]

I am having the problem all of a sudden but it is NOT router or bit slippage. The Z will suddendly raise by an inch at random times. I tried rebooting my computer, regenerating the tap file, lubricating the machine...nothing helps. It has to be either a servo issue (overheating maybe although I am only cutting an 1/8 nch deep so I doubt that is it), a software issue or a board (controller) issue. Need help desperately. With this machine doing this I am losing money and time I cannot afford.
Please help.
Thanks,
Ross.

[Wolffie1]

I am having the problem all of a sudden but it is NOT router or bit slippage. The Z will suddendly raise by an inch at random times. I tried rebooting my computer, regenerating the tap file, lubricating the machine...nothing helps. It has to be either a servo issue (overheating maybe although I am only cutting an 1/8 nch deep so I doubt that is it), a software issue or a board (controller) issue. Need help desperately. With this machine doing this I am losing money and time I cannot afford.
Please help.
Thanks,
Ross.

You are exactly right.
Slippage will not cause the router or bit to RAISE only to lower.
I have had that problem too and called the machine some rather bad names.
I have also had the Z shifting in the YZ position.
Only solution was to start all over again with everything crossed hoping that nothing will go wrong.
Cheers
Wolffie